The main objective of this study is to develop a methodology adapted to the prospective environmental evaluation of actions in the energy sector. It describes how a bottom-up long-term energy model can be used in a life cycle assessment (LCA) framework. The proposed methodology is applied in a case study about the global warming impacts occurring as a consequence of the future production of synthetic diesel from biomass ("biomass to liquids"-BTL), a secondgeneration biofuel, in France. The results show a high sensitivity of the system-wide GHG balance to (i) the policy context and to (ii) the economic environment. Both influence the substitutions occurring within the system due to the production of BTL. Under the specific conditions of this study, the consequences of introducing BTL are not clear-cut. Therefore, we focus on the lessons from the detailed analysis of the results more than in the precise-looking projections, illustrating how this type of models can be used for strategic planning (industry and policy makers). TIMES-type models allow a detailed description of the numerous technologies affected by BTL production and how these vary under different policy scenarios. Moreover, some recommendations are presented, which should contribute for a proper systematization of consequential and prospective LCA methodologies. We provide argumentation on how to define a functional unit and system boundaries that are better linked with the goal of the study. Other crucial methodological issues are also discussed: how to treat temporal aspects in such environmental evaluation and how to increase the consistency of life cycle assessments.

International audienceThe objective of this study is to improve evaluations of the future use of biomass sources in Sweden and France by representing the high spatial variations of the supply and cost of biomass sources in energy system models. The proposed methodology considers a high spatial disaggregation of biomass supply sources, as well as detailed biomass cost-supply curves, and is thereby able to account for spatial differences in heterogeneous land qualities, management strategies, and possible adaptation rates. Integrating the methodology into national or regional energy system models will enhance cost-effective evaluations of biomass sources as well as the development of the bioenergy sector. A TIMES energy system model was used to evaluate bioenergy production potential for France and Sweden based on domestic biomass sources and under the assumption that bioenergy production should not be at the expense of domestic food and forestry supply. Results show that by 2050, the biomass sources considered could provide as much as 250PJ of bioenergy in Sweden, and 1470PJ of bioenergy in France. Results further showed that 1st generation biofuels are likely to continue to play a substantial role in the biofuel mix. While 2nd generation biofuel production in Sweden is likely to be low, larger amounts of 2nd generation biofuels could be produced in France. However, the amount and type of 2nd generation biofuel produced in France was found to be highly dependent on the bioenergy demand level

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Résumé -Ester d'acide gras en Europe : tendances de marché et perspectives technologiques -En raison d'un système initialement fortement incitatif mis en place par l'Union Européenne, la production d'ester d'acide gras (EAG) commence à s'étendre et à gagner le monde. Un examen approfondi du système complexe de compensations financières proposé par les états membres et une mise à jour annoncée en matière d'augmentation des capacités de production de biodiesel peuvent permettre de dégager les facteurs de succès de cette expansion aussi brutale que soudaine. Ce tissu de données économiques et législatives démontre l'existence de solutions technologiques alternatives pertinentes permettant de pérenniser ce succès. En effet, cette hausse de la production attendue d'EAG engage de plus en plus à se soucier de l'optimisation et de la rationalisation des unités de forte capacité pour qu'elles utilisent la meilleure technologie disponible visant des rendements élevés tout en veillant au respect de l'environnement, particulièrement au regard de la co-production de déchets. Cet article présente une technologie alternative permettant d'apporter une réponse originale à ce problème, technologie mettant en oeuvre un catalyseur hétérogène pour la transesterification des huiles végétales. Ce procédé s'appuie sur la réaction de méthanolyse des huiles végétales, réaction réalisée sur deux réacteurs successifs en lit fixe, suivie par des étapes de séparation du méthanol en excès et de la glycérine de l'ester méthylique formé. Ce procédé ne requiert ni section de récupération du catalyseur, ni traitement de rejet aqueux. Il montre un haut rendement en ester méthylique, proche de la limite thermodynamique. La conversion peut égale-ment être ajustée sans avoir recours à une consommation de catalyseur complémentaire. La glycérine co-produite possède directement une pureté de 98 % et est exempte de contaminants sous forme de sels ou de savons. L'absence de rejets et la qualité des produits fait que ce procédé est, au-delà de l'aspect 'environmentally friendly' inhérent à ses produits, un « procédé vert ». Abstract -Fatty Acid Esters in

The case study is defined in the context of the French law on the energy transition (LTECV: Loi relative à la Transition Energétique pour la Croissance Verte, referred to as LTE here) published in August 2015 (Assemblée nationale and Sénat de France 2015). The law proposes a set of targets to tackle climate change, preserve the environment and enhance energy independence in France. In the transport sector, the main objective of the LTE is to "develop clean transports to enhance the air quality and protect the health of French people". Its implementation is done with two targets: (i) 15% renewable energy consumption in the transport sector and (ii) a reduction of 30% in fossil primary energy consumption by 2030 as compared to the 2012 level.